Prior to the advent of ceramic brackets, it has been known to provide metal brackets with bonding pads for direct bonding the brackets to teeth. The bonding pads are also of metal and are suitably secured to the brackets. Removal has been accomplished by the use of a standard dental pliers and can be accomplished with respect to all of the brackets in a matter of minutes.
Ceramic brackets made of monocrystalline or polycrystalline material have posed a different problem when they are bonded to teeth, as it is difficult to debond the brackets following their use.
Bonding materials of various types have been used, some of which have greater bonding strength than others. These bonding materials are made and sold by a number of orthodontic supply companies. Ceramic brackets have their bases integrally formed. Such ceramic brackets are often molded and/or machined to final shape. It is a well known problem that removal of bonded ceramic brackets has proved quite difficult and can be very hazardous. For example, when a rigid bracket is removed directly from a tooth, it may cause the bracket to fracture, leaving a part of the bracket on the tooth. The other part of the bracket might shatter in the patient's mouth, setting up a situation where pieces of the bracket which are like glass might be ingested, inhaled or might otherwise damage the tissues of the mouth.
When a part of the ceramic bracket is left on the tooth, it often requires grinding to be removed, and damage can easily be done to the tooth enamel.
Also, it has been known to remove part or all of the enamel during the removal of ceramic brackets, which then is injurious to the health of the tooth. Whenever enamel is removed or the patient injured by the removal of a ceramic bracket, a potential liability problem is created for the orthodontist.
Unlike the time needed to remove metal brackets, the time needed to remove ceramic brackets is substantially greater, which then not only requires more time of the orthodontist but makes the chair time of the patient more uncomfortable.
Ceramic brackets are known to be much more rigid than metal brackets which can somewhat flex or bend during removal. Because of the inability of ceramic brackets to flex, it can be appreciated that greater forces usually are required to remove the bracket during debonding. Whenever the bracket to adhesive interface between a ceramic bracket and the tooth enamel is too strong, there is a high potential for damage of the enamel during debonding. Several attempts have been made to solve the debonding problem associated with ceramic brackets. For example, it is proposed in U.S. Pat. No. 4,455,138 that heat to the dental bracket will assist in loosening the adhesive bonding of the bracket to the tooth so that the bracket may be more easily removed with less forces. However, it has been found that this system was not always practical as the orthodontist may prematurely pull the bracket in anticipation of the loosening of adhesive, causing great pain to the patient and also shattering of the bracket before the heat applied would loosen the adhesive. Further, the pulling force could not be directionally controlled with this system.
Another debracketing tool and method of removal is disclosed in U.S. Pat. No. 4,907,965, where the heat and debracketing force is simultaneously applied. This system does not always assure that the adhesive is sufficiently loose to allow easy removal, and likewise requires engagement of the ceramic bracket during removal.
It is also known to provide a relatively flexible bonding pad or base for an orthodontic bracket to facilitate debonding as disclosed in U.S. Pat. No. 5,098,288. However, it has been found that the bonding between the pad and the bracket often fails during treatment due to the various forces on the bracket during treatment, thereby necessitating rebonding. In such instances, treatment has been interrupted delaying the ultimate conclusion of treatment, and costly chair time is required to rebond the bracket to the tooth.
Further, it has been known to provide a compliant mesh screen of low-density polyethylene between a ceramic bracket and a tooth as disclosed in U.S. Pat. No. 5,110,290. This patent also suggests the compliant layer may be a polyethylene sheet with a plurality of openings.